In addition to WiFi, Global Positioning Systems (GPS), Near Field Communications (NFC), and cellular communications, mobile communication devices increasingly also provide a method for wireless charging. Wireless charging solutions are typically based on a multi-turn conductive loop (coil) that is configured to respond to magnetic fields. This multi-turn coil configuration is commonly nested within the NFC antenna structure.
A wireless charging coil is often placed behind the back housing of a mobile communication device. Portable communication devices such as cellular phones have typically incorporated a non-conductive back housing (e.g. plastic), or an appropriate opening in a conductive back housing, to allow an embedded wireless charging coil to freely operate. The opening is generally necessary, since otherwise the magnetic fields generated by the wireless power transmitter unit (drive coil) would be blocked and not reach to the receiver in the mobile device. In essence, the receptive coil would be trapped between the conductive internal components of the mobile device and the conductive housing. Thus, internal wireless charging coils typically require an open (nonconductive) path through the back of the device.
In an effort to deliver more premium electronic devices to consumers, cellular phone manufacturers are increasingly employing exterior housings fabricated from metal alloys. In addition, mobile communication devices are handled frequently, and plastic housings are weaker than metal ones of similar thickness, hence allowing more frequent damage and breakage. Similarly, a metal housing with an opening over an internal wireless charging coil is still weaker than a unibody metal construction, is more expensive and complex to manufacture than a unibody construction, and is aesthetically less pleasing than a unibody construction.
Before proceeding, it should be appreciated that the present disclosure is directed to a system that can eliminate some of the shortcomings noted in this Background section. However, any such benefit is not a limitation on the scope of the disclosed principles, or of the attached claims, except to the extent expressly noted in the claims. Additionally, the discussion of technology in this Background section is reflective of the inventors' own observations, considerations, and thoughts, and is in no way intended to accurately catalog or comprehensively summarize any prior art reference or practice. As such, the inventors expressly disclaim this section as admitted or assumed prior art. Moreover, the identification herein of desirable courses of action reflects the inventors' own observations and ideas, and should not be assumed to indicate an art-recognized desirability.